1. Field of the Invention
The present invention relates to a gauge for measuring the length of an opening, and more particularly to such a gauge operable with one hand and adapted for use where there is access to only one end of the opening.
2. Description of the Prior Art
There are a number of devices which are adapted to determine the length of an opening through an element where access can be had from only one end of the opening. However, most of these devices do not provide positive assurance that the gauge is firmly anchored in position upon the far edge of the opening prior to engagement of the near edge of the opening by another portion of the gauge. In the absence of this certainty of anchorage, the gauge can become disengaged from the far edge of the opening and provide an erroneous indication of the length of the opening.
Precise determination of the length of an opening is particularly important in surgical procedures. For example, in any operation requiring the use of bone screws for fixation of a fracture, either directly or through the use of adjunctive hardward such as metal plates, the exact length of the screws required must be determined. This cannot be measured directly because exposure to the bone opening is usually limited to one surface of the bone.
One prior device for measuring the proper length of screw in such a surgical procedure comprises a length of wire with a hook on one end and a sliding lock nut. The wire is inserted into the bone and the hook is engaged on the far edge or far outer cortex of the bone. The sliding member is brought to the near surface of the bone and tightened. Next, the wire is removed and the wire portion approximating the length of the opening is measured with an ordinary ruler. Such a procedure is cumbersome, requires the use of two hands, requires the use of a separate ruler, and is unreliable in that the wire often becomes bent and the hook is difficult to properly engage upon the far cortex of the bone.